US3901352A - Underwater reflector of sound waves - Google Patents

Underwater reflector of sound waves Download PDF

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Publication number
US3901352A
US3901352A US494909A US49490974A US3901352A US 3901352 A US3901352 A US 3901352A US 494909 A US494909 A US 494909A US 49490974 A US49490974 A US 49490974A US 3901352 A US3901352 A US 3901352A
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United States
Prior art keywords
reflector
filaments
enclosure
mesh
acoustic
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Expired - Lifetime
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US494909A
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English (en)
Inventor
Philippe Henri Maurice Cluzel
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Gouvernement de la Republique Francaise
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Gouvernement de la Republique Francaise
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    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/18—Methods or devices for transmitting, conducting or directing sound
    • G10K11/20—Reflecting arrangements
    • G10K11/205—Reflecting arrangements for underwater use

Definitions

  • ABSTRACT Foreign Application Priority Data An underwater reflector of sound waves adapted for Aug. 16, 1973 France .1 73.29805 use at great depths and comprising a hermetic enclosure constituted of a flexible material capable of un- [52] S Cl 81/1 5; 1 /33 340/8 FT dergoing deformation, a stack of mesh members being [51] Int. Cl. G10K 11/00 mounted between two rigid plates within the enclo- [58] Field Of r h 340/3 8 8 sure. Each mesh member is constituted by crossed fil- 181/400, 402, .5; 343/18 B; 181/33 E, 33 G, aments and preferably interlaced metallic filaments. 33 GA, 33 GD, 33 GE, 33 R, 175
  • One utilization is the forming of reflector surfaces or screens of acoustic antennas for emitter or receiver [56] References Cited purposes.
  • the present invention relates to acoustic sound reflectors adapted for use at great depths of immersion in a body of water.
  • the invention is particularly concerned with the construction of a submersible acoustic reflector for serving as a receiver and an emitter of acoustic waves.
  • the reflectors presently utilized underwater in submarines or the like, are generally based on this property.
  • Water has a relatively high acoustic impedence and rigid materials, notably metals, have an impedence which is, at a maximum, three times that of water.
  • light materials such as a gas, cork, or cellular material
  • a gas, cork, or cellular material have an impedence much lower than water and have therefore been utilized for their great impedence difference with water for submerged reflectors.
  • these light materials are compressed or crushed, their mechanical impedence is lowered and the reflector rapidly loses its efficiency at relatively great depths.
  • An object of the invention is to provide a reflector adapted for use at great depths of immersion of about several hundreds of meters and whose efficiency is substantially independent of pressure for the frequency bands currently used in acoustic submarines.
  • a reflector formed by a sealed enclosure containing a flexible and deformable material comprising at least one mesh member of crossed filaments placed between two rigid plates.
  • mesh member of crossed filaments is intended to embrace all structure formed of filaments having substantially point-like regions of contact.
  • Perforated sheets, punched sheets, developed metal sheets are not included in this term as these structures form sheets in which the sound waves travel easily; also the contacts between superposed sheets are in the form of surface areas and the sound waves pass easily from one sheet to another.
  • the reflective power of such an assembly of plates is not good. As reflectors such as structures have a certain reflective power beyond IOKH but at lower frequencies the reflective power is very poor.
  • mesh members with crossed filaments have the property that the sound waves are poorly transmitted not only between juxtaposed members but also in the plane of a member because the contact between the filaments is substantially point-wise.
  • a member has a certain thickness and can be deflected by its elastic flexure.
  • the filaments of the members are made of a metal whose acoustic impedence is greater than that of water.
  • wire mesh of any other rigid material having a coefficient of elasticity sufficient to resist crushing.
  • Rigid plates are placed on opposite sides of the assembly of juxtaposed mesh members for the purpose of transmitting hydrostatic pressure from the flexible enclosure to the mesh member in contact therewith, while distributing the pressure between the points of contact with this member.
  • the hardness of these plates is determined as a function of the number of points of contact of the surfaces in contact for resisting the compression stresses.
  • These plates and the juxtaposed mesh members which are elastically and deformably interposed therebetween form an elastic system having a regular frequency of oscillation which depends on the weight of the plates. The dimensions thereof are determined for this frequency whereas the frequency of vibration in flexure of the plates is situated outside the frequency band to be reflected in order to avoid all resonance phenomena with the acoustic waves.
  • These plates can be, for example, metallic or statified polyester.
  • the external enclosure has the function of preventing entry of water into the mesh openings of the mesh member.
  • the enclosure is made of deformable material in order to transmit the hydrostatic pressure to the rigid plates placed in contact with its faces, and therefore it can not resist pressure differences.
  • Elastomer material such as natural or artificial rubber or flexible plastic material are suitable to form this enclosure.
  • juxtaposed modular units each comprising a sealed enclosure.
  • the enclosures of one or a plurality of units are accidentally broken, the other units remain intact and the reflector will only lose a small part of its reflective power.
  • the mounting of a reflector on a non-planar surface is easier if the reflector is formed of juxtaposed elements.
  • the invention contemplates the production of a submersible reflector of acoustic waves adapted for immersion to great depths.
  • Such reflector has the advantage of high reflective power with a relatively reduced thickness of the order of 1 to 2 cm. which, in spite of a small weight, remains high even at great depths of tens of meters of water. Another advantage resides in the fact that the reflective power is high over an extended frequency band currently utilized in acoustic submarines, notably at low frequencies.
  • a reflector according to the invention can be utilized to form acoustic wave projectors or focussing mirrors, or response screens permitting marking a location under water from the echos of sonar waves reflected by said screen.
  • FIG. 1 is a perspective view partly broken away and in section of a reflector unit according to the invention.
  • FIG. 2 is a perspective view of an assembly of reflector units to form an acoustic antenna.
  • FIG. 1 shows a reflector unit designated by numeral 1 and composed of a plurality ofjuxtaposed members 2a, 2b, 20 formed of crossed metallic filaments sand wiched between two rigid thin plates 3a, 3b, the assembly being placed in an enclosure 4 which is hermetically sealed and deformable.
  • each member being formed of interlaced warp and weft filaments which confer a thickness to the member of about two times the thickness of the filaments.
  • the assembly of members can deform by the flexure of the filaments around the points of contact between the members.
  • the number of members can be other than three, either being reducible to a single member or increased above three.
  • the size of the filaments and the mesh openings is selected as a function of the pressure.
  • the number of points of Contact between the members and between the filaments of the same member is substantially smaller as the mesh size increases.
  • the travel of the acoustic waves in the member is therefore especially reduced as the size of the mesh openings increases and the reflective power is greater.
  • the flexural stresses are also greater if the mesh size is increased and there is a risk of obtaining permanent deformation at high pressures.
  • the plates 3a and 3b are thin metallic sheets having a thickness of about 1 mm. They can also be a Stratified synthetic resin.
  • the enclosure 4 is made of natural or artificial rubber.
  • the member 2 of interlaced filaments can be replaced by a member of crossing filaments which are joined at the crossing points by ties or spot welding; however the reflective power is lowered at high pressures.
  • FIGS. 2 shows an acoustic antenna serving as an emitter or receiver of the type utilized in acoustic submarines.
  • the antenna is composed of hydrophones 6 which are electro-acoustic transducers for emitters or receivers.
  • the hydrophones are mounted on rigid support 7.
  • each unit 8a is constituted of a sealed enclosure containing one or more mesh members of crossed filaments interposed between two rigid plates.
  • surface 8 is planar. It could also have a cylindrical, polygonal, or spherical form in order to constitute a focussing mirror or a projector formed with a great number of modules 8a.
  • the units 8a can be planar or curved.
  • An underwater reflector of acoustic waves adapted for high hydrostatic pressures comprising a sealed enclosure of flexible, deformable material, at least one mesh element of crossed filaments, and two rigid plates sandwiching the element therebetween to form an assembly, said assembly being hermetically sealed in said enclosure.
  • a reflector as claimed in claim I wherein a plurality of said elements are provided in superposed rela tion.
  • a reflector as claimed in claim 1 wherein a plurality of said enclosures are assembled in juxtaposed relation to form a reflective surface.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Aerials With Secondary Devices (AREA)
  • Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
US494909A 1973-08-16 1974-08-05 Underwater reflector of sound waves Expired - Lifetime US3901352A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR7329805A FR2240813B1 (enrdf_load_stackoverflow) 1973-08-16 1973-08-16

Publications (1)

Publication Number Publication Date
US3901352A true US3901352A (en) 1975-08-26

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ID=9124019

Family Applications (1)

Application Number Title Priority Date Filing Date
US494909A Expired - Lifetime US3901352A (en) 1973-08-16 1974-08-05 Underwater reflector of sound waves

Country Status (4)

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US (1) US3901352A (enrdf_load_stackoverflow)
DE (1) DE2435336A1 (enrdf_load_stackoverflow)
FR (1) FR2240813B1 (enrdf_load_stackoverflow)
GB (1) GB1465932A (enrdf_load_stackoverflow)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4031502A (en) * 1975-04-11 1977-06-21 Etat Francais Hydrophone with acoustic reflector
US4160230A (en) * 1976-03-08 1979-07-03 Etat Francais Acoustic antenna
US4197920A (en) * 1978-03-23 1980-04-15 Etat Francais Represented By The Delegue General Pour L'armement Underwater acoustic reflectors
US4674595A (en) * 1985-11-20 1987-06-23 The United States Of America As Represented By The Secretary Of The Navy Underwater acoustic pressure release baffle for depths to 2000 feet
RU2138858C1 (ru) * 1998-08-17 1999-09-27 Центральный научно-исследовательский институт имени академика А.Н.Крылова Подводный акустический экран
WO2010150090A1 (en) 2009-06-25 2010-12-29 Defence Research & Development Organisation An acoustic energy reflector
US20130105243A1 (en) * 2010-07-16 2013-05-02 Carl Peter Tiltman Acoustic reflectors
US8857368B2 (en) 2011-09-21 2014-10-14 The Boeing Company Aircraft location system for locating aircraft in water environments
CN111928736A (zh) * 2020-06-18 2020-11-13 天津科技大学 一种原位自膨胀水下伪装体
US11335311B2 (en) * 2017-04-26 2022-05-17 Dalian University Of Technology Broadband ultrathin acoustic wave diffusion structure

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2536195A1 (fr) * 1982-11-17 1984-05-18 Sintra Alcatel Sa Reflecteur acoustique sous-marin
FR2539541B1 (fr) * 1983-01-19 1986-09-19 Thomson Csf Dispositif a interface reflectrice d'ondes acoustiques
GB2204217B (en) * 1987-05-02 1990-05-23 Gec Avionics Acoustic reflector
GB2422282A (en) 2005-01-14 2006-07-19 Secr Defence Acoustic reflector
GB2458810B (en) * 2008-04-01 2010-05-05 Secr Defence Acoustic reflector
JP5068385B2 (ja) 2008-04-02 2012-11-07 イギリス国 調節可能な音響反射器
CN110580896A (zh) * 2019-08-29 2019-12-17 罗家骏 一种水下真空角反射器

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1974951A (en) * 1929-11-18 1934-09-25 Doorentz Richard Sound damping intermediate layer for ceilings, walls, and the like
US2811216A (en) * 1954-04-28 1957-10-29 Harris Transducer Corp Acoustic baffle construction
US2884084A (en) * 1954-10-28 1959-04-28 Sussman Harry Acoustic panel
US3756345A (en) * 1972-02-10 1973-09-04 Honeywell Inc Underwater acoustic device

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1974951A (en) * 1929-11-18 1934-09-25 Doorentz Richard Sound damping intermediate layer for ceilings, walls, and the like
US2811216A (en) * 1954-04-28 1957-10-29 Harris Transducer Corp Acoustic baffle construction
US2884084A (en) * 1954-10-28 1959-04-28 Sussman Harry Acoustic panel
US3756345A (en) * 1972-02-10 1973-09-04 Honeywell Inc Underwater acoustic device

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4031502A (en) * 1975-04-11 1977-06-21 Etat Francais Hydrophone with acoustic reflector
US4160230A (en) * 1976-03-08 1979-07-03 Etat Francais Acoustic antenna
US4197920A (en) * 1978-03-23 1980-04-15 Etat Francais Represented By The Delegue General Pour L'armement Underwater acoustic reflectors
US4674595A (en) * 1985-11-20 1987-06-23 The United States Of America As Represented By The Secretary Of The Navy Underwater acoustic pressure release baffle for depths to 2000 feet
RU2138858C1 (ru) * 1998-08-17 1999-09-27 Центральный научно-исследовательский институт имени академика А.Н.Крылова Подводный акустический экран
US8485315B2 (en) 2009-06-25 2013-07-16 Defence Research & Development Organisation Ministry of Defence Acoustic energy reflector
WO2010150090A1 (en) 2009-06-25 2010-12-29 Defence Research & Development Organisation An acoustic energy reflector
US20130105243A1 (en) * 2010-07-16 2013-05-02 Carl Peter Tiltman Acoustic reflectors
US8910743B2 (en) * 2010-07-16 2014-12-16 Subsea Asset Location Technologies Limited Acoustic Reflectors
US8857368B2 (en) 2011-09-21 2014-10-14 The Boeing Company Aircraft location system for locating aircraft in water environments
US9296491B2 (en) 2011-09-21 2016-03-29 The Boeing Company Aircraft location system for locating aircraft in water environments
US11335311B2 (en) * 2017-04-26 2022-05-17 Dalian University Of Technology Broadband ultrathin acoustic wave diffusion structure
CN111928736A (zh) * 2020-06-18 2020-11-13 天津科技大学 一种原位自膨胀水下伪装体
CN111928736B (zh) * 2020-06-18 2022-11-11 天津科技大学 一种原位自膨胀水下伪装体

Also Published As

Publication number Publication date
FR2240813B1 (enrdf_load_stackoverflow) 1976-04-30
GB1465932A (en) 1977-03-02
DE2435336A1 (de) 1975-03-06
FR2240813A1 (enrdf_load_stackoverflow) 1975-03-14

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